Flight 370: Whole world listens for slowly fading pings

Story highlights

  • Two data recorders are fitted with beacons
  • Battery life is about a month
  • Pings generally detected up to 2 nautical miles

Somewhere in the vast Indian Ocean, a tiny aluminum cylinder may be emitting a steady ping.

The ping itself is unremarkable, says Anish Patel, president of beacon manufacturer Dukane Seacom Inc. Patel snaps his fingers to match the pinger's rate -- one snap per second. In fact, it is inaudible to human ears.

But the whole world is listening. And the ping is taking on the cadence of a slowly failing clock.

Friday marks the 14th day of the hunt for Malaysia Airlines Flight 370, and near the halfway mark in the pinger's minimum battery life. When the battery dies, possibly around April 6, the job of finding the flight data and cockpit voice recorders will get significantly harder. And so will the job of solving the mystery of Flight 370.

A beacon of hope

Bill Nye: We will find Flight 370
Bill Nye: We will find Flight 370


    Bill Nye: We will find Flight 370


Bill Nye: We will find Flight 370 00:53
How do ocean recoveries work?
How do ocean recoveries work?


    How do ocean recoveries work?


How do ocean recoveries work? 03:44
New video shows search for Flight 370
New video shows search for Flight 370


    New video shows search for Flight 370


New video shows search for Flight 370 02:11

Every commercial airplane is required to have pingers -- technically called underwater locator beacons -- to help locate lost aircraft. One is attached to the flight data recorder; another to the cockpit voice recorder. Find the pingers and you find the recorders. Find the recorders, experts say, and you solve the mystery of Flight 370.

But, like virtually everything in aviation, the current technology represents one step in an evolutionary path. Today's recorders are better than recorders of the past, when data was recorded on magnetic tape. But they fall short of current technical potential, with short battery lives and -- on voice recorders -- only two hours of recording capacity.

Since Flight 370 flew almost seven hours beyond the point where something went terribly wrong, it's almost guaranteed that crucial cockpit sounds have been erased.

On the positive side, the depletion of the battery will not wipe out data. Data has been known to survive years in harsh sea water conditions on modern recorders.

The latest questions and answers

Standards today

Cockpit voice recorders memorialize pilot's words -- from the inconsequential to the tragic. In 1999, a voice recorder captured the last words of the startled captain of EgyptAir 990 as he fought to maintain control of his plane. The cockpit voice recorder helped establish that the pilot was trying to pull the plane out of a dive while his co-pilot flew it into the ocean.

Voice recorders also record clicks and hums -- sounds that can reveal pilot's actions.

Flight data recorders capture a wide array of data, including altitudes, air speeds, headings, engine temperatures, flap and rudder positions.

"The newer aircraft typically are to record 88 or 91 parameters now, but usually we see recorders that come in for the newer aircraft of at least a few hundred parameters if not more than 1,000," a National Transportation Safety Board official said.

They must record the previous 36 hours of operations.

Enter the data into a flight simulator, and you can re-create history, using technology to solve a technological mystery.

But first you have to find the boxes.

Data recorders are built to withstand the rigors of flight and the trauma of crashes.

Are flight recorders too outdated?
Are flight recorders too outdated?


    Are flight recorders too outdated?


Are flight recorders too outdated? 02:33
Expert: Three scenarios for Flight 370
Expert: Three scenarios for Flight 370


    Expert: Three scenarios for Flight 370


Expert: Three scenarios for Flight 370 04:29

Recorders are required to survive short, hot blazes, such as a fuel fire, or longer but cooler blazes, such as a forest fire, were a plane to crash in the woods.

They are required to survive an impact shock of 3,400 G-forces, and have standards for static crush and fluid immersion.

They must be able to withstand hydrostatic pressures found at 20,000 feet deep. The region where searchers are now looking for Flight 370 has depths up to 13,000 feet.

The pingers are activated upon immersion in fresh or salt water, and emit a signal at 37.5 kilohertz.

To detect the signals, searchers drag hydrophones behind boats, drop them from ships or planes, or use specially equipped submersibles.

Under favorable sea conditions, the pingers can be heard 2 nautical miles away. But high seas, background noise, wreckage or silt can all make pingers harder to detect.

Hear what the pingers would sound like

What does the 'ping' sound like?
What does the 'ping' sound like?


    What does the 'ping' sound like?


What does the 'ping' sound like? 01:41

Changes since Air France 447

The 2009 crash of Air France 447 was a game changer in the history of underwater beacons. The battery died before searchers could locate the wreckage. It was another two years before the recorders were recovered.

Since then, regulators and the airline industry have undertaken efforts to increase the beacon battery life from 30 to 90 days. And there are efforts to require pingers to be attached to aircraft airframes, making it easier to locate wreckage. The next-generation pingers emit pings that can be heard 6 to 10 miles away, said Patel.

Ocean search has many challenges

After 30 days

Patel believes his company manufactured the pingers on Malaysia 370.

"We are confident it could be one of ours," he said. Malaysia Airlines is a customer of Dukane Seacom, and the company's pingers have been installed on Boeing 777s.

"We're preparing to address questions should it be ours," he says.

And what is happening now with the pingers?

If it's not found soon, Malaysia 370's pingers may die with a whimper.

After 30 days, the battery will continue providing power and the beacon will ping, but the output will quickly drop, Patel says.

"As the battery 'wears down' the pinger output decreases until the battery reaches a point that no ping is emitted," Patel wrote in an e-mail to CNN. "The pings get lower and lower in 'volume' as the battery weakens."

"Our predictive models and lab tests show 33-35 days of output before we drop below the minimal value," he wrote. "Depending on the age of the battery, it could continue pinging for a few days longer with progressively lower output levels, until the unit shuts down."

Clues lead to theories

      Malaysia Airlines Flight 370

    • nr intv moni basu husbands quiet suffering flight 370_00020822.jpg

      An empty space on earth

      His wife never came home from her flight on MH370, and now K.S. Narendran is left to imagine the worst of possible truths without knowing.
    • This handout photo taken on April 7, 2014 and released on April 9, 2014 by Australian Defence shows Maritime Warfare Officer, Sub Lieutenant Ryan Penrose watching HMAS Success as HMAS Perth approaches for a replenishment at sea while searching for missing Malaysia Airlines flight MH370 in the southern Indian Ocean. Two fresh signals have been picked up Australian ship Ocean Shield in the search for missing Malaysian flight MH370, raising hopes that wreckage will be found within days even as black box batteries start to expire.

      Is this the sound of the crash?

      Was the sound of Malaysian Airlines Flight MH370 striking the water captured by ocean devices used to listen for signs of nuclear blasts?
    •  A crew member of a Royal New Zealand Airforce (RNZAF) P-3K2-Orion aircraft helps to look for objects during the search for missing Malaysia Airlines flight MH370 in flight over the Indian Ocean on April 13, 2014 off the coast of Perth, Australia. S

      Search back to square one

      What was believed to be the best hope of finding the missing plane is now being called a false hope. Rene Marsh explains.
    • Caption:A Chinese relative of passengers on the missing Malaysia Airlines flight MH370 uses a lighter as she prays at the Metro Park Hotel in Beijing on April 8, 2014. The hunt for physical evidence that the Malaysia Airlines jet crashed in the Indian Ocean more than three weeks ago has turned up nothing, despite a massive operation involving seven countries and repeated sightings of suspected debris. AFP PHOTO/WANG ZHAO (Photo credit should read WANG ZHAO/AFP/Getty Images)

      Bring in the lawyers

      Involved parties, including the manufacturer Boeing, are bracing for a long public relations siege.
    • The painstaking search for Malaysia Airlines Flight 370 got a vote of confidence Friday that the effort is headed in the right direction, but officials noted that much work remains.
Credit: 	CNN

      Pings likely not from Flight 370

      Official: The four acoustic pings at the center of the search for Flight 370 are no longer believed to have come from the plane's black boxes.
    • INDIAN OCEAN (April 14, 2014) -- Operators aboard ADF Ocean Shield move U.S. Navy's Bluefin-21 into position for deployment, April 14. Using side scan sonar, the Bluefin will descend to a depth of between 4,000 and 4,500 meters, approximately 35 meters above the ocean floor. It will spend up to 16 hours at this depth collecting data, before potentially moving to other likely search areas. Joint Task Force 658 is currently supporting Operation Southern Indian Ocean, searching for the missing Malaysia Airlines Flight 370. (U.S. Navy video by Mass Communication Specialist 1st Class Peter D. Blair/RELEASED)

      Underwater search on hold

      The underwater search for the missing Malaysia Airlines plane will effectively be put on hold this week, and may not resume until August at the earliest.
    • Movie-makers say they have recruited leading Hollywood technicians to bring their experience to mid-air flight sequences.

      An MH370 movie already?

      Movie-makers in Cannes have announced they're making a thriller based on the disappearance of Malaysian flight MH370.
    • The story of the search

      The search for the missing Boeing 777 has gone on for eight weeks now. CNN's David Molko looks back at this difficult, emotional assignment.